What is the Solar System?
The Solar System consists of the Sun and all the objects that orbit (move around) it due to its gravity. This includes:
- The Sun (our star).
- Eight Planets.
- Dwarf planets (like Pluto).
- Satellites (Moons).
- Asteroids, Comets, and Meteoroids.
The Sun
The Sun is the center of our Solar System.
- Type: It is a star.
- Composition: An extremely hot, spherical ball of gases (mostly hydrogen and helium).
- Significance: It is the ultimate source of heat and light for the Solar System. Without the Sun, life on Earth would not exist.
- Size: It is huge—about 100 times wider than Earth in diameter.
- Distance: It is about 150 million kilometers away from Earth.
Tip
Astronomical Unit (au): The average distance between the Sun and the Earth (approx. 150 million km) is defined as 1 Astronomical Unit. It is used to measure distances within the solar system.
Why does the Sun look so big?
The Sun looks like a large disk, while other stars look like pinpoints. This is because the Sun is much closer to us than any other star. The next nearest star, Proxima Centauri, is about 269,000 au away!
Revolution and Rotation
- Revolution: The movement of an object around the Sun. Earth takes ~365 days to complete one revolution.
- Rotation: The spinning of an object on its own axis. Earth takes 24 hours to complete one rotation (causing Day and Night).